Purpose of argc and argv in SDL Applications

int argc (argument count) and char** argv (argument vector/values) are the standard way C and C++ programs receive command-line arguments when they are launched from a terminal or shell.

argc: An integer representing the number of arguments passed to the program. It's always at least 1, because the program's name itself is considered the first argument.

argv: An array of C-style strings (char*):

• argv[0] is typically the name/path used to invoke the program.
• argv[1] is the first actual argument provided by the user.
• argv[2] is the second argument, and so on.
• argv[argc] is guaranteed to be a null pointer.

Example: If you run your program from the command line like this:

1./mygame -level 5 --fullscreen

Then inside main:

argc would be 4.

argv would look something like this (conceptually):

• argv[0]: "./mygame"
• argv[1]: "-level"
• argv[2]: "5"
• argv[3]: "--fullscreen"
• argv[4]: nullptr

Your program could then parse argv to configure itself based on these user-provided options (e.g., load level 5, start in fullscreen mode).

Do You Need Them in This SDL Program?

In the simple SDL program presented in the lesson so far, argc and argv are not being used directly by our C++ code. We haven't written any code to parse command-line arguments.

1// We receive argc and argv but don't use them
2int main(int argc, char** argv) {
3  SDL_Init(SDL_INIT_VIDEO);
4  Window GameWindow;
5  // ... loop ...
6  SDL_Quit();
7  return 0;
8}

So, strictly speaking, for the code as written, you could potentially use the alternative standard signature int main():

1// Alternative signature if arguments are not used
2int main() {
3  // ... same code ...
4}

Why Keep Them in SDL Programs?

Despite not using them directly yet, it's common practice to keep the int main(int argc, char** argv) signature in SDL applications for a few reasons:

1. Future Use: You might decide later to add command-line options for debugging, configuration, or different startup modes. Keeping the standard signature makes this easy.
2. SDL's SDL_main: On some platforms (particularly Windows and macOS when creating GUI applications without a console window), SDL uses a technique where it defines its own main function (SDL_main). This SDL_main performs some platform-specific setup and then calls your main function, passing along potentially modified argc and argv. To ensure compatibility with this mechanism across all platforms SDL supports, it's safest and conventional to declare your main with the standard int main(int argc, char** argv) signature.
3. Convention: Most C and C++ tutorials and examples use this signature, so it's familiar.

In summary: While not strictly necessary for the current simple example's functionality, keeping int main(int argc, char** argv) is the standard, most portable, and future-proof convention for SDL applications. It doesn't cause any harm if the arguments aren't used.